Present self-routing networks use the same switching fabric to implement both the control and data switching operations of the network. One such self-routing network that utilizes the same switching fabric for control and data is disclosed in U.S. Pat. No. 4,494,230, by J. S. Turner, entitled, "Fast Packet Switching System". The system disclosed in Turner utilizes address bits contained within packets to route these packets through the switching fabric.
Other prior art systems maintain a network map in the memory of a computer controlling the network. In response to a request to establish a path through the network, the controlling computer executes a program that is responsive to the stored network map to determine the required connections within the network to establish the requested path. The computer then communicates the connection information to the network which utilizes the connection information to establish the path. One well-known system that operates in this manner, is disclosed in the article by D. Danielsen, K. S. Dunlap, and H. R. Hofmann, "No. 1 ESS Switching Network Frames and Circuits, "The Bell System Technical Journal, Vol. XLIII, No. 5, Part 2, pp. 2221-2253, September 1964. Whereas, it is known to maintain a memory map in a computer memory and to use program control to establish a path through the network, this operation requires a number of access points into the network and increases the cost and lowers the reliability of the network. In addition, the advantages of a self-routing network cannot be utilized.
Certain types of network technologies that have the capability for transmitting data at extremely high bandwidths are not well suited for performing the control operations. One such technology is the titanium diffused lithium niobate used for photonic switching. The reason why photonic switching technologies have difficulty in performing the control functions is that data path crossovers are very difficult to implement. The reason for this difficulty is that efficient waveguide crossovers require large angles of intersection in order to minimize the interface between adjacent waveguides. These large angles require that there to be large S-bends in the intersecting waveguides which are themselves lossy. Thus, efficient integrated waveguide crossovers in titanium diffused lithium niobate are very difficult to fabricate. Additional information on this problem can be found in the article by E. E. 8ergmann, et al., "Coupling of Intersecting Ti:NbO.sub.3 Diffused Waveguides".
In view of the foregoing, there exists a need for a self-routing switching architecture that is capable of taking advantage of switching networks that are well-suited for performing the control functions and the use of switching networks that are capable of transmitting large bandwidths of data without being burdened with the control functions.